This project proposes a comprehensive intervention aimed at structurally transforming the management of treated effluent generated by the municipal Wastewater Treatment Plant (WWTP) located in the eastern part of the autonomous community of Aragón, Spain. The main objective is to convert this currently underutilized resource into a safe, hygienically suitable, traceable water flow, technically compatible with pressurized irrigation systems, thus contributing to closing the urban-agricultural water cycle in a region of high water vulnerability.
The initiative aligns with the international Volumetric Water Benefit Accounting (VWBA) 2.0 framework, which allows for transparent quantification, certification, and reporting of benefits obtained by substituting conventional water sources, such as aquifers or surface intakes, with high-quality reclaimed water. This approach reinforces the principle of additionality, promotes territorial climate resilience, and enables environmental valorization of water resources.
The project is located in an area of significant agri-livestock dynamism, with an intensive production model centered around extensive maize and forage cultivation, along with a large-scale meat processing industry. This set of activities creates a seasonally concentrated demand for water, exerting significant pressure on available resources from the Alcanadre River and the shallow aquifers of Bajo Cinca. Despite this, the treated effluent from the local WWTP is currently discharged into the receiving body without being harnessed, representing a structural loss of a potentially valuable resource.
The intervention seeks to reverse this pattern through the implementation of technological solutions that allow for the valorization of the effluent, its integration into pressurized irrigation networks in coordination with local irrigation communities, and the assurance of operational and sanitary traceability. The project is envisioned as a concrete water adaptation measure capable of generating quantifiable, permanent, and verifiable volumetric water benefits.
The Wastewater Treatment Plant (WWTP) receives and treats a significant daily flow of wastewater originating both from the urban core and from local agri-industrial activities, particularly the meat processing industry and the cleaning of agricultural equipment. Nevertheless, this treated effluent is discharged directly into the receiving water body without being subjected to any valorization or reuse process, even though its output quality would allow for the implementation of an efficient tertiary treatment system.
At the same time, the region’s productive matrix, based on high-water-demand crops and intensive livestock farming, relies predominantly on surface water withdrawals from the Alcanadre River and extractions from shallow aquifers. This creates a structurally stressed water scenario, where the balance between water supply and demand remains under constant strain, particularly during peak agricultural demand periods. This pressure is exacerbated by factors such as declining groundwater levels, reduced natural recharge capacity, and diminished environmental flows.
The current model not only fails to utilize a resource with agronomic and energetic potential, but it also imposes unnecessary burdens on fluvial ecosystems and lacks integration between urban and industrial water cycles. The absence of a structured reuse strategy limits the transition toward a resilient territorial model based on circular water economy principles. This gap represents a critical opportunity to redesign the system, reduce reliance on conventional sources, and enable new regional water security frameworks.
The proposed technical solution involves the implementation of an advanced tertiary treatment system capable of transforming the WWTP’s secondary effluent into Class A quality regenerated water, in strict compliance with the sanitary criteria defined by Royal Decree 1620/2007 and its forthcoming update, Royal Decree 1085/2024. The treatment train is designed to ensure the effective removal of solids, pathogenic microorganisms, viruses, residual nutrients, and emerging contaminants, enabling its safe use in agricultural irrigation involving direct contact with food crops.
The system will begin with a membrane ultrafiltration stage using membranes with a pore size below 0.1 microns, effectively eliminating total suspended solids, colloidal matter, bacteria, and protozoa. This stage acts as a robust physical barrier, providing a stable and homogeneous water quality for subsequent phases. It will be followed by a high-intensity ultraviolet (UV) disinfection reactor, dimensioned to ensure complete inactivation of enteric viruses and resistant bacteria, meeting UV dose thresholds of over 40 mJ/cm².
As an additional sanitary safety measure, an inline sodium hypochlorite dosing system will be installed, designed to maintain a residual free chlorine concentration between 0.5 and 1.0 mg/L during transport to the point of use. This dual microbiological barrier (UV + chlorination) ensures sanitary quality throughout the entire distribution chain, even in the face of potential operational fluctuations.
The system will be integrated with a modular-capacity intermediate storage unit, equipped with real-time sensors for level, temperature, and water quality, from which the regenerated water will be pumped into a pressurized irrigation network. All operations will be monitored via a SCADA platform with real-time communication, water quality sensors (turbidity, UV transmittance, free chlorine), and auditable digital records. This ensures continuous compliance with regulatory parameters, traceability of treated volumes, and verification of water benefits in accordance with international sustainability standards.
The project will be implemented in three successive stages, designed to ensure additionality, operational traceability, and permanence of the generated water benefits. Each phase includes specific measurement instruments, applied technologies, and monitoring and control mechanisms.
Stage 1: Technical Assessment and Engineering Design (Months 0–6): This phase involves a comprehensive characterization of the secondary effluent treated at the Binéfar WWTP. Key parameters to be measured include physicochemical indicators such as pH, conductivity, turbidity, biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), and total suspended solids, as well as microbiological indicators such as total coliforms and Escherichia coli.
The data obtained will inform the hydraulic and sanitary design of the tertiary treatment train. Selected components include ultrafiltration modules with a pore size below 0.1 µm, UV disinfection reactors, and a dosed chlorination system. Additionally, quality control points will be defined, and the permitting process will begin with the Ebro River Basin Authority and regional health authorities.
Stage 2: Construction, Equipment Installation and Operational Testing (Months 6–12): Civil works will be carried out for the installation of the selected equipment. This includes support structures, hydraulic interconnections, intermediate storage tanks, pumping stations, and pressurized conveyance pipelines. Ultrafiltration modules, UV disinfection reactors, sodium hypochlorite dosing systems, and inline sensors will be installed.
Calibrated sensors will monitor turbidity (threshold < 2 NTU), UV transmittance, free chlorine (0.5–1 mg/L), and delivered flow. The SCADA system will be configured to integrate and record real-time operational data. System validation will be completed with water quality testing by an accredited laboratory to verify compliance with national sanitary regulations.
Stage 3: Commissioning, Continuous Operation and Monitoring (From Month 12 onward): The system enters sustained operation with daily delivery of regenerated water to connected irrigation communities. Continuous monitoring will be carried out through the SCADA system with inline sensors, complemented by quarterly external validation from accredited independent laboratories.
Auditable digital records will be maintained to document treated volumes, microbiological compliance (absence of E. coli), and overall system performance. A feedback mechanism will be established to adjust operational conditions based on effluent quality, climatic variations, or seasonal agricultural requirements.
This stage ensures the permanence of water benefits through formal supply agreements with end users and the integration of the system into local water planning strategies. Annual reviews will also be conducted to assess the model’s effectiveness and its potential scalability to other municipalities or agricultural sectors in the region.
This project proposes a structural transformation in the management of treated effluent from the wastewater treatment plant located in the municipality of Binéfar, in Aragón. Its objective is to convert an underutilized water resource into a safe and operationally secure source of regenerated water, intended for use in advanced agricultural irrigation within a region characterized by high seasonal demand and growing water stress. The intervention is aligned with the Volumetric Water Benefit Accounting (VWBA) methodology, version 2.0, applying the criteria set out in Appendix A-4 to quantify water benefits through the substitution of conventional sources with treated alternative sources.
The project’s area of influence follows an intensive agri-livestock production model, based on maize and forage crops and supported by a robust livestock industry. This productive structure relies primarily on surface and groundwater sources, exerting constant pressure on regional water balance. At the same time, the municipal treatment plant discharges its secondary treated effluent daily into the receiving water body, without any reuse system in place. This situation constitutes a structural inefficiency that undermines both environmental sustainability and the region’s water resilience.
The technical proposal involves the implementation of a complete tertiary treatment system composed of a high-precision membrane ultrafiltration line, a high-intensity ultraviolet disinfection unit, and a secondary chlorination barrier to ensure microbiological safety during water transport. This treatment sequence is designed to meet current sanitary requirements for reclaimed water in agricultural applications, especially for crops involving direct contact. The regenerated water is stored in an intermediate unit and pumped through controlled-pressure networks to agricultural distribution systems.
The system is integrated with automation and continuous monitoring platforms that ensure traceability, quality standard compliance, and periodic external verification of results. Operational digitalization through inline sensors and remote supervision allows real-time documentation of key parameters such as turbidity, free chlorine, UV transmittance, and delivered flow, enabling certification of water benefits in accordance with international sustainability schemes.
The project is implemented through three progressive stages. The first stage involves technical and sanitary characterization of the effluent and design of the treatment train adapted to local conditions. This includes the development of hydraulic specifications and the processing of environmental and health permits. The second stage comprises civil works, installation of technological modules, and full system calibration, including leak testing, functional validation, and operational commissioning. In the third stage, the system enters continuous operation, supplying regenerated water to irrigation communities, with constant monitoring of sanitary parameters, digital traceability, and independent technical auditing.
The intervention takes place within a river basin that has been internationally recognized as a priority by the CEO Water Mandate due to high competition for water resources, degradation of aquatic ecosystems, and vulnerability to climate change. As such, this project represents not only an effective measure for water efficiency but also a strategic component for territorial adaptation and environmental restoration.
Expected benefits include a reduction in withdrawals from natural sources, improved resilience of the regional agricultural system, preservation of environmental flows, and effective integration of urban and industrial water cycles. At the same time, the project contributes directly to multiple Sustainable Development Goals, including food security, clean water access, innovation, climate action, and institutional partnerships.
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